Double layer tape seal on container slit opening



July 1, 1969 D. R. AVQLIO DOUBLE LAYER TAPE SEAL ON CONTAINER SLITOPENING Filed April 5, 1968 Sheet of 3 INVENTOR. D.R. AVOLI O BY wf'wj AT TORNEVS y 1, 1969 D. R. AVOLIO 3,452,919

DOUBLE LAYER TAPE SEAL 0N CONTAINER SLIT OPENING Filed April 5, 1968Sheet 2 of 3 INVENTOR. D.R. AVOL IO AT TORNEYS July 1, 1969 D. R. AVOLIO3,452,919

DOUBLE LAYER TAPE SEAL ON CONTAINER SLIT OPENING Filed April 5, 1968Sheet 3 of s F G. 4 INVENTOR.

on. AVOLIO BY 2mg);

A TTORNEVS United States Patent US. Cl. 229-17 9 Claims ABSTRACT OF THEDISCLOSURE A polyethylene-backed aluminum foil tape is heat sealed overthe area on a gable top plastic coated paperboard milk carton blankwhere the slit opening is to be die cut. Subsequently the opening is diecut through both the tape and the blank. A second polyethylene-backedaluminum foil tape is sealed over the slit in the first tape. Theformed, filled and sealed carton is opened by peeling the second tapefrom the first tape, leaving a neat appearing, sanitary slit opening.

Gable top containers of the type disclosed in Wilcox, U. S. 3,295,739,are formed of thermoplastic coated paperboard and are provided with aweakened line of severance to form the pouring lip when the container isopened. The weakened line of severance is covered in the sealedcontainer by a tape which is heat sealed to the thermoplastic coating onthe container. When this tape is removed from the container in theprocess of initially opening the container, the adhesion between thetape and the thermoplastic coating on the paperboard exceeds thestrength of the outer fibrous layer of the paperboard with the resultthat the outer layer of fibers is removed, leaving a roughened fibroussurface. Although this roughened surface has the advantages of being afresh, clean, sterile surface, it permits the paperboard to readilyabsorb part of the liquid contents being poured from the container.While this does not present any significant disadvantages with milk, dueto the similarity in color to the paperboard, severe discloration isexperienced with other liquids which differ in color from thepaperboard. Furthermore, the roughened surface reduces the aestheticvalue of the container even in the absence of discloration.

In accordance with the invention, it has been discovered that theforegoing disadvantages can be avoided by bonding a first tape to thecontainer blank prior to forming the slit or weakened line of severance,cutting the weakened line of severance through the first tape and theblank, and subsquently utilizing a second tape over the first tape toseal the weakened line of severance in the first tape. The first tape isa laminate with the back surface being a thermoplastic material which iscompatible with and heat sealable by welding, or mutual fusion, to thethermoplastic coating on the container blank to form a bond which isstronger than the bond between the fibers in the paperboard substrate ofthe container blank. The outer surface of the first tape is a nonporousmaterial which has a melting point substantially higher than the meltingpoint of the thermoplastic backing of the first tape of thethermoplastic backing of the second tape. The thermoplastic backing ofthe second tape is heat sealable by hot melt adhesion to the outersurface of the first tape to form a peelable bond, which is preferablyweaker than the bond between the fibers in the fiberboard. In initiallyopening a formed and sealed container, the second tape is peeled fromthe first tape leaving the smooth, attractive outer surface of the firsttape on the spout lip.

Accordingly, it is an object of the invention to provide an improvedcontainer having a weakened line of severance protected by a tape. It isan object of the invention to eliminate the raw paperboard edge on acontainer spout opening caused by delamination of the paperboard uponremoval of a cover tape. Another object of the invention is to increasethe ease of opening a container having a weakened line of severancecovered by a sealing member. A further object of the invention is toenhance the aesthetic value of a container. Another object is tominimize contact of the liquid contents of a container with rawpaperboard during dispensing.

Other objects, aspects and advantages of the invention will be apparentfrom a study of the specification, the drawings and the appended claimsto the invention.

In the drawings, FIGURE 1 is a perspective view of a gable top containerto which the invention is applicable; FIGURE 2 is a plan view of thepaperboard blank, having the first tape thereon, from which thecontainer of FIGURE 1 is formed; FIGURE 3 is a perspective View of thegable top structure of the container of FIGURE 1 in a partially openedcondition; and FIGURE 4 is a perspective view of the gable top structureof FIGURE 3 in the fully opened condition.

Referring now to FIGURE 2, the rectangular blank of paperboard having acoating of polyethylene on front and back, is provided with verticalscore lines 12, 13, 14 and 15, extending upwardly from the lower edge ofthe blank to a series 16 of horizontally extending score lines 16a, 16b,16c, 16d, and 16:2. The score lines 13, 14 and 16b define a front sidewall panel 17. Score lines 15 and 16d, and 12 and 16a define panels 18and 19, the free edges of which, in the formed container, are overlappedand joined by a permanent adhesive bond to form a rear side wall panelwhich is located opposite front side panel 17. End wall panels 21 and 22are defined by score lines 12, 13 and 16a and 14, 15 and 160,respectively. Horizontal score lines 16a and 16c are located lower onthe container than score lines 16b, 16d and 16e to substantially reducethe thickness of the folds at adjacent lower corners of the closurepanels. In other words, the spacing apart in the vertical plane of thebend of each roof panel into its vertical container wall from the bendof each end closure panel into its vertical container wall permitssmaller and more attractive folds in the resulting corners of thecontainer. With the scoring arrangement shown in FIGURE 2, the panels17, 21, 22 and the rear wall panel formed by panels 18 and 19 are all ofequal width.

The vertical score lines 12, 13, 14 and 15, which are located at thevertical corners of the completed container, extend upwardly past scorelines 16 as 23, 24, 25 and 26, and terminate at the top edge of theblank. Horizontal score line 27 is located a short distance downwardlyfrom the top edge of the blank.

When the blank has been folded to tubular form and overlapping edges ofthe panels 18 and 19 have been joined together, a bottom closure 20(FIGURE 1) is permanently sealed to the lower end of the tubularformation. Score lines 24, 25, 16b and 27 define the front roof closurepanel 28. Score lines 24, 25 and 27 define the rib panel 29, surmountingthe front roof panel 28. Score lines 23, 26, 16a, 16e and 27 define therear roof closure panel composed of sections 31 and 32. Score lines 26,23 and 27 define the rib panel, comprising sections 33 and 34,surmounting the rear roof panel. Score lines 23, 24, 16a and 27 define arectangular end closure panel. This end closure panel is provided withconverging score lines 35 and 36 which, at their upper ends, intersectthe score line 27 medial of score lines 23 and 24, thus defining atriangular end closure panel portion 37 and a pair of triangularfoldback panel portions 38 and 39. Score lines 23, 24, 27 and 41 definerib panels 42 and 43,

surmounting fold-back panel portions 38 and 39, respectively. Scorelines 25, 26, 16c and 27 define a second rectangular end closure panel.This second end closure panel is provided with converging score lines 44and 45 which, at their upper ends, intersect score line 27 medial ofscore lines and 26, thus defining a triangular end closure panel portion46 and a pair of triangular fold-back panels 47 and 48. Score lines 25,49, 26 and 27 define ridge panels 51 and 52, surmounting fold-back panelportions 47 and 48, respectively. In the completed container, the pairof opposed roof panels 28 and 31, 32 are inclined toward each other andoverlie the top of the tubular body formed by side walls 17, 21, 22 and18, 19. The pair of opposed triangular end closure panels 37 and 46 areinfolded between roof panels 28 and 31, 32 from the opposite gable endsformed by the latter, and with their apexes located at the central areaof the gable. The fold lines 44, 45, 35 and 36 which join each pair oftriangular fold-back panels 47, 48 and 38, 39 to the opposite sides oftriangular end closure panels 46 and 37 are in proximity with the roofpanels, the fold-back panels being folded against the underside of saidroof panels. Ridge panels 51 and 52 surmounting fold-back panels 47 and48 are hinged together at the apex of end closure panel 46 and arefolded about the hinge joinder score line 49 in face-to-face relation,between the ridge panels 29 and 33 surmounting the roof panels.Similarly, ridge panels 42 and 43 surmounting fold-back panels 38 and 39are hinged together at the apex of end closure panel 37 and are foldedabout the hinge joinder score line 41 in face-to-face relation, betweenridge panels 29 and 34. The ridge panels are heated to form a bondbetween the contacting thermoplastic coatings to form the ridgestructure of the gable top.

Score lines 23, 24, 25 and 26 are of extended width, with respect to theremainder of score lines 12, 13, 14 and 15, with the extension being ina direction toward the center of the respective roof panel. Thus scorelines 24 and 25 are of extended width in the direction of the center ofthe front roof panel 28, while score lines 23 and 26 are of extendedwidth in a direction toward the center of the rear roof panel formed bypanels 31 and 32.

When the blank of FIGURE 2 is folded on the score lines 12, 13, 14 and15 about the square mandrel of the container erecting machine, theclosure panels above the series of score lines 16 form a square tubularcross section in a direction transversely of the container. When the topclosure panels are folded inwardly, the greater width of score lines 23,24, 25 and 26 provides extra material for the end closure panels 46, 47,48 and 37, 38, 39 and surmounting rib panels 51, 52 and 42, 43, wherebyin the formed and sealed container, rib panels 43 and 51 have a greatercombined length than rib panel 29 surmounting the front roof panel 28.Similarly rib panels 52 and 42 have a greater combined length in theformed and sealed container than the rib panel formed by panels 33, 34surmounting the rear roof panel 31, 32. This, in turn, results in thehinge joints on score lines 41 and 49 abutting or slightly overlappingat the center of the laminar ridge structure formed by bonding the ribpanels together.

In order to provide a snap action for opening and closing the pouringspout, the front roof panel 28 is provided with score lines 71 and 72,extending upwardly from the intersection of horizontal score line 16band vertical score line 25 to a point on score line 27 midway betweenvertical score lines 24 and 25. Score line 71 is preferably formed inthree sections 71a, 71b and 71c. Score line 72 is preferably formed inthree sections 72a, 72b and 720. Straight line sections 71b and 72b aresubstantially parallel to an imaginary line 73 between the point onscore line 27 midway between score lines 24 and 25 and the intersectionof score lines 16b and 25.

Imaginary line 73 closely approximates the plane of the triangular endclosure panel 46 in the infolded, sealed condition. If side walls 17 and18, 19 were of greater width than walls 21 and 22, score line sections71a and 72a would intersect score line 27 at or closely adjacent to theintersection of imaginary line 73 with score line 27, or in other wordsat or closely adjacent to the intersection of the score line 27 with theplane of panel 46 in the infolded, sealed condition of the container.Score section 72b is positioned in roof panel 28 above the imaginaryline 73 while score section 71b is positioned in roof panel 28 belowimaginary line 73. Score sections 710 and 720 extend from the lower endsof score sections 71b and 72b, respectively, to converge together at theintersection of score lines 16b and 25. Score sections 71a and 72aextend from the upper ends of score sections 71b and 72b, respectively,to the point on score line 27 midway between score lines 24 and 25. Therear roof panel 31, 32 is provided with score lines 74 and 75,corresponding to score lines 71 and 72, respectively, comprising scoresections 74a, 74b, 74c, and 75a, 75b, 75c, respectively.

In the second end closure panel, which serves as the pouring spout,converging score lines 44 and 45 intersect horizontal score line 27midway between score lines 25 and 26. Vertical score line 49 extendsupwardly from the intersection of score lines 44 and 45 to the top edgeof the blank. A first tape 66 comprising a backing layer of polyethylenelaminated to an outer layer of aluminum foil is heat sealed to thesecond end closure panel by mutual fusion of the backing layer to thepolyethylene coating on the blank. The weakened line of severance orslit is located in the upper part of panel portions 47, 46 and 48 belowhorizontal score line 27 and extends through both the blank and tape 66.The weakened line of severance is formed in three sections, each endsection 60a and 60b being formed by a series of zig-zag incisions, andthe center section 600 being formed by a straight, horizontal incision.The weakened line of severance 60 would intersect score lines 44 and 45except that score lines 44 and 45 are discontinuous, or interrupted, inthe area of the weakened line of severance 60. Score lines 44 and 45stop short of line 60 to prevent leakage which could otherwise occur bycapillary action through the slit and along the score lines. Eliminatingall score line grooves in the vicinity of the line 60 provides a fiatsurface completely around the periphery of the slit, thus permitting aliquid tight seal to be effected between the first, or inner, tape 66and the container, and also a liquid tight seal between the first tape66 and the second, or outer, tape 61 (FIGURE 3).

A second strip of tape 61 (FIGURE 3) comprising a backing layer ofpolyethylene laminated to an outer layer of aluminum foil, is peelablyheat sealed to the outer aluminum layer of tape 66 in overlying relationto the weakened line of severance 60. The tape 61 is applied over theweakened line of severance 60 and heat sealed to the entire marginalsurface about the weakened line of severance.

The first tape 66 is heat sealed to the blank prior to the formation ofthe weakened line of severance 60, while tape 61 is preferably bonded totape 66 after the blank has been folded on score lines 12, 13, 14 and 15to form a tubular body, but prior to the continued folding of the blankto form the gable top structure. This eliminates possible damage to theseal between tapes 61 and 66 would could occur during the handling ofthe blanks if tape 61 were added earlier, and minimizes the possibilityof accidently causing a fold along the weakened line of severance duringthe formation of the gable top structure. The ends 62 of tape 61 extendbeyond the ends of the second end closure panel to provide graspingtabs, while tape 66 does not extend outside of the second end closurepanel. In one embodiment, tape 66 is stopped short of the edge of thesecond end closure panel to permit a fusion type heat seal between thepoleythylene coating on the end closure panel and the portion of tape 61which overlies the exposed portion 67 (FIGURE 3) of the end closurepanel. This tacking of tape 61 at the outer ends of tape 66 minimizesthe possibility of accidental separation of tape 61 from tape 66.

During the initial opening of the container of FIGURE 1, outwardlydirected pressure is applied against panels 47 and 48 to delaminate thebond between panels 51 and 52 and the panels 47 and 48 are foldedoutwardly and backwardly (toward the opposite gable end) to the positionillustrated in FIGURE 3. One end 62 of tape 61 is grasped and tape 61 ispeeled from tape 66, leaving the clean, attractive, unspoiled aluminumfoil surface of tape 66 as the exterior surface of the lip of thepouring spout. Panels 47 and 48 are then folded further backward andinwardly directed pressure is applied along fold lines 25 and 26 to popout the lower portions of panels 46, 47 and 48 to form the pouring spoutillustrated in FIGURE 4.

While tapes 61 and 66 have been described in terms of the presentlypreferred laminated aluminum foil tape having a polyethylene backing,tapes of other materials can be employed. The backing layer of the firsttape should be a thermoplastic material which is compatible with andheat sealable by mutual fusion to the thermoplastic coating on thepaperboard blank. It is presently preferred that the backing of thefirst tape be the same thermoplastic material which is utilized to coatthe paperboard. Various homopolymers of ethylene or propylene andcopolymers of ethylene or propylene with each other and/or with at leastone other mono-l-olefin having from 4 to carbon atoms per molecule or adiolefin having from 4 to 10 carbon atoms per molecule, and polymers ofvinyl chloride alone or with suitable comonomers can be employed as thebacking for the second tape as well as the backing for the first tapeand as the coating for the paperboard. The outer layer of the first tapeshould be nonporous to prevent or minimize mechanical bonding with thebacking of the second tape and should have a melting point above themelting point of the backing for the first tape as well as above themelting point of the backing of the second tape to prevent mutual fusionwith the backing of the second tape and sticking to the sealingequipment for applying the first tape to the blank. Suitable materialsfor the outer layer of the first tape include metal foils, for examplealuminum foil, tin foil; polyesters, for example polyethyleneterphthalate; polyamides, for example nylon; fiber glass; cellophane;and papers or fibrous material sized with a high temperature sizing, forexample sodium silicate. While the outer layer of the second tape can beof any of the materials given for the outer layer of the first tape, itis presently preferred that the outer layer of the second tape be of aheat reflective material, such as a metal foil, to protect the bond ofthe first tape to the container and the bond of the second tape to thefirst tape during the radiant heating of the ridge panels preparatory tothe formation and sealing of the gable top structure.

While the invention has been described in terms of a particular type ofgable top container, it is applicable to other types of paperboardcontainers utilizing a cover sheet to protect an opening therein.

Reasonable variations and modifications are possible within the scope ofthe foregoing disclosure, the drawings and the appended claims to theinvention.

I claim:

1. A container formed of paperboard coated with a first thermoplasticmaterial, a first cover sheet having a backing surface of a secondthermoplastic material compatible with and heat sealed to said firstthermoplastic material by mutual fusion, said first cover having anouter surface of a nonporous material having a melting pointsignificantly above the melting point of said second thermoplasticmaterial, an opening in said container through said first cover sheet, asecond cover sheet hav ing a backing material of a third thermoplasticmaterial which has a melting point significantly below the melting pointof the outer surface material of said first cover sheet and which isheat sealed to the outer surface of said first cover sheet entirelyaround said opening by a peelable bond to seal said opening.

2. A container in accordance with claim 1 wherein a portion of saidsecond cover sheet extends beyond said first cover sheet and the backingmaterial of a first part of said portion is heat sealed by mutual fusionto said first thermoplastic material and a second part of said portionis unbonded, thereby providing a grasping tab.

3. A container in accordance with claim 1 wherein each of said first,second and third thermoplastic materials is a polymer of ethylene, andsaid outer surface material of said first cover sheet is a metal foil.

4. A container in accordance with claim 1 wherein said container is agable top container having a pouring spout panel, said opening being aweakened line of severance in said pouring spout panel.

5. A contatiner in accordance with claim 4 wherein said gable topcontainer comprises a tubular body, a bottom closure fixed to said body,a pair of opposed roof panels inclining toward each other and overlyingthe top of said body, a pair of opposed triangular end closure panelsinfolded between said roof panels from the opposite gable ends formed bythe latter, first and second pairs of triangular fold-back panels, eachpair of triangular fold-back panels being joined to the opposite sidesof a respective one of said triangular end closure panels along foldlines which are in proximity with said roof panels, said fold-backpanels being folded against the underside of said roof panels, a ridgepanel surmounting each of said roof panels, a ridge panel surmountingeach of said fold-back panels, each pair of ridge panels surmounting apair of fold-back panels being hinged together at the apex of thecontiguous end closure panel and being folded about such hinge joinderin face-to-face relation, between the ridge panels surmounting said roofpanels.

6. A container in accordance with claim 5 wherein said opening is aweakened line of severance located in the rectangular end closure panelformed by one of said triangular end closure panels and its associatedpair of triangular fold-back panels, said weakened line of severancelying solely within the upper portion of said reetangular end closurepanel below the respective surmounting ridge panels and extendingtransversely of said rectangular end closure panel and terminating atits ends in spaced relation to the side edges of said rectangular endclosure panel.

7. A container in accordance with claim 6 wherein the outer surface ofsaid second cover sheet is a radiant heat reflective material.

8. A container in accordance with claim 7 wherein each of said first,second and third thermoplastic materials is a polymer of ethylene.

9. A container in accordance with claim 8 wherein the outer surface ofeach of said first and second cover sheets is a metal foil.

References Cited UNITED STATES PATENTS 3,217,966 11/1965 Kelly 229-l73,295,739 l/l967 Wilcox 229-17 3,348,755 10/1967 MacEwen 229l7 DAVID M.BOCKENEK, Primary Examiner.

U.S. Cl. X.R. 229-37, 51

